The invention relates to a metal-ceramic substrate to a method for producing one such metal-ceramic substrate and a module, particularly a semiconductor power module with a metal-ceramic substrate.
Metal-ceramic substrates, also copper-ceramic substrates for electric circuits, particularly for semiconductor power circuits or modules, are known in a wide variety of designs. Also known in particular for the manufacture of strip conductors, connectors, etc. is the application of a metallization on a ceramic, e.g. on an aluminum-oxide ceramic by means of the so-called “DCB process” (direct copper bond technology), said metallization being formed from metal or copper foils or metal or copper sheets, the surfaces of which include a layer or a coat (hot-melt layer) from a chemical bond between the metal and a reactive gas, preferably oxygen. In this method, which is described, for example, in US PS 37 44 120 and in PS 23 19 854, this layer or coat (hot-melt layer) forms a eutectic with a melting temperature below the melting temperature of the metal (e.g. copper), so that the layers can be bonded to each other by placing the foil on the ceramic and heating all layers, namely by melting the metal or copper essentially only in the area of the hot-melt layer or oxide layer.
This DCB process then includes, for example, the following process steps:                a) oxidation of a copper foil so as to produce an even copper oxide layer;        b) placing the copper foil on the ceramic layer;        c) heating the composite to a process temperature between approx. 1025 and 1083° C., e.g. to approx. 1071° C.;        d) cooling to room temperature.        
Electric circuits or modules, particularly power circuits or modules with a power element and a control or drive element have heretofore been manufactured in the manner that a metal-ceramic substrate is used as a substrate or circuit board for the power element and that the control or drive circuit on a separate circuit board assembled with its components is then mounted by suitable means in a second level above the power element or next to the latter on the metal-ceramic substrate.
The disadvantage of this method, for example, is the high cost of manufacture, since the power element and the control or drive stage must be manufactured separately and then connected and bonded together in production. In particular, this known technology does not allow the multiple manufacture of the entire module (power element+control and driver stage) in accordance with the principles of efficient production.
It is an object of the invention to present a metal-ceramic substrate which enables the particularly efficient production of circuits, particularly semiconductor circuits and especially power circuits with a corresponding control and driver stage.